1. Field of the Invention
The present invention relates to an electric motor and, more particularly, to a rotor structure of an electric motor.
2. Description of the Background Art
A shading coil types, single-phase induction motor is constructed such that a stator forms a rotating magnetic field and a stator coil of single phase, and another phase of shading coil are installed at a position of being rotated at a certain angle spatially with respect to the stator coil so that an induction rotor is rotated by an oval-shaped rotating magnetic field to thereby generate a rotational force.
Though the shading coil type single-phase induction motor has a low efficiency, it is advantageous in that it can be implemented at a low cost, and as such, it is widely used for light load use such as a fan motor for a refrigerator, an electric fan for domestic use, etc.
However, the conventional shading coil type single-phase induction motor has the following problems.
That is, in spite of the advantage of implementation of the low-priced motor, a loss is generated from the shading coil to degrade efficiency of the motor. In addition, since a driving force for driving the induction rotor is not uniformly generated, vibration occurs which accompanies a noise.